The present invention generally relates to electrical discharge machining. More particularly, the present invention relates to an apparatus and method for electrical discharge machining of multiple holes.
Multiple hole drilling using electrical discharge machining (EDM) is accomplished by using a multiple tooling assembly which is also known as a Acomb-tool.@ The tooling assembly includes a plurality of fixed or non-rotating electrodes mounted on a ram of an EDM machine. A drawback with such a tooling assembly is that it is difficult to flush the dielectric fluid from small, deep holes, and therefore the process is extremely slow, and only suitable for drilling multiple non-circular holes.
High speed electrical discharge machining uses a spinning tubular electrode, a dielectric fluid and high pressure flushing through the electrode center for drilling a single circular hole.
Some high speed EDM machines incorporate a pair of spindles mounted in proximity to one another for spinning a pair of electrodes for machining a pair of holes simultaneously. In such a system each spindle operates independently having separate motor drives and control systems for each electrode. A system of this type is significantly more costly than a single spindle system, and the spindles are in a fixed position in relation to one another, making adjustment difficult if not impossible.
Therefore, a need exists for a high speed EDM capable of drilling multiple holes at the same time and in which a plurality of rotatable electrodes are adjustably positioned in relation to one another. The above-mentioned needs are satisfied by the present invention which provides, in a first aspect, an apparatus for electrical discharge machining multiple holes in an electrically conductive work piece, in which the apparatus includes an electrical discharge machine for rotatably mounting a first electrode, the electrical discharge machine comprising a driver and a controller, at least one electrical discharge unit for rotatably mounting at least one second electrode, wherein the driver is coupled to the electrical discharge machine and the electrical discharge unit for rotating the first electrode and the at least one second electrode, and the controller is coupled to the electrical discharge machine and the at least one electrical discharge unit for controlling a supply of electrical energy from the first electrode and second electrode to the workpiece.
In a second aspect, a device is provided for use with an electrical discharge machining machine for machining multiple holes in a work piece in which the device includes a plurality of electrical discharge units for rotatably mounting a plurality of electrodes and a drive mechanism coupled to the plurality of electrical discharge units and couplable to a driver of the electrical discharge machine for rotating the plurality of electrodes.